Method and apparatus for the cleaning of closed compartments

ABSTRACT

An apparatus for cleaning the inside surfaces of a tank with a jet of fluid from a nozzle lowered into the interior of the tank. The nozzle is capable of being rotated around a first axis and also capable of being swivelled upward and downward in an oscillating movement around a second axis at right angles to the first axis in a predetermined manner. A drive mechanism for the nozzle includes a turbine driven by a stream of fluid with a drive connected to the turbine.

BACKGROUND OF THE INVENTION

The invention relates to an apparatus for the cleaning of the insidesurfaces of a tank or similar space by means of a jet of fluid from anozzle lowered into the interior of the tank, said nozzle being capableof being rotated around a first axis and also swivelled, oscillated,around a second axis at right-angles to said first axis in apredetermined manner, so that the jet of fluid is traversed around atthe same time that it is moved upwards and downwards inside the tank andcomprising a turbine driven by a stream of fluid which, via a drive,gives rise to rotation of the nozzle.

The interior of a tank, such as an oil storage tank on a ship,containers, vessels and the like, must at intervals be cleaned of sludgeand other impurities which are deposited on the inside surfaces of thetank.

This is usually carried out by means of a cleaning apparatus which canbe mounted permanently on the tank, and which is provided with a nozzlemounted on the end of a shaft which extends a suitable distance downinto the tank.

The nozzle is supplied with cleaning fluid under pressure which isdischarged while the nozzle is brought to move in a predeterminedpattern, so that the cleaning fluid systematically hits and sweeps allsurfaces and hereby dissolves and flushes away the sludge deposits whichhereafter can be led out together with the fluid.

By means of a drive unit in the apparatus, the nozzle can both be turnedaround in relation to the shaft in a horizontal plane and swung up anddown in a vertical plane. It is hereby ensured that the cleaning patternis one which ensures an effective sweeping of all surfaces.

From U.S. Pat. No. 3,874,594 a tank washing machine with selective washprogramming is known, in which washing liquid is discharged from anozzle mounted on a housing which is rotatable about a first axis (e.g.vertical) in relation to other normally fixed parts of the machine. Thenozzle is rotatable or pivotable about a second axis (e.g. horizontal).The second axis is therefore for instance perpendicular to the first. Asingle driving means (preferably a single turbine powered by washingliquid) is connected via gears and a clutch mechanism to rotate thehousing about the first axis and via other gears to pivote or rotate thenozzle about the second axis, the ratio of the angular speeds of thenozzle and housing about their respective axes being constant, but theabsolute angular speeds being varied in accordance with a selectedprogram.

By choosing different washing programmes, the speed of rotation of thenozzle about the first axis, and the speed of oscillation about thesecond axis can be altered to meet the requirements of the particulartank being cleaned.

The programmes are selected by the profile of a cam and a shift betweendifferent programmes is done by a shift to another profiled cam.

This is difficult and timeconsuming because the only possibility ofaltering the program is to change the cam, and the nozzle movement andherewith the cleaning pattern are not easily altered, which means thatfurther cleaning time and cleaning fluid must be used in such caseswhere the cleaning is not adequate and must therefore be repeated untilall deposits are removed. In practise, this will typically be in thecorners in the bottom of the tank.

OBJECT OF THE INVENTION

It is therefore the object of the invention to provide an apparatuswhich by a simple mechanical drive can provide a stepless variablesetting of the swinging movement of the nozzle in that the drive of theapparatus must be able to withstand the tough surroundings of a tankvessel.

This object is achieved by an apparatus of the type disclosed in thepreamble, which apparatus according to the invention is characteristicin that the drive also turns a worm shaft and a worm wheel, said wormwheel being provided with a stud which is in sliding engagement with aconnecting link, the other end of which is in sliding engagement with astud on a first pinion which, upon rotation of the worm wheel, turns thefirst pinion forwards and backwards, said first pinion being inengagement with a rack which, at its opposite end, is in engagement witha second pinion on the nozzle, so that the nozzle effects a swivellingmovement.

ADVANTAGES OF THE INVENTION

In the event of a tank being extremely dirty, the apparatus according tothe invention permits stepless setting to a tightly-meshed pattern ofmovement for the nozzle, which ensures the most effective cleaning inthe shortest possible cleaning time in that the drive, apart from havinga simple construction in terms of its operation, is also strong andoffers an effective swinging movement of the nozzle.

The apparatus according to the invention also makes it possible to varythe oscillating speed of the nozzle in a stepless manner duringoperation so as to obtain an effective cleaning, in that the density ofthe track of the jet, and thus its intensity, can be adjusted to suitrequirements. This will save time, cleaning fluid as well as energy, inthat the distance between the jets during rotation inside the tank canbe adjusted to provide a perfect cleaning result.

Also, by adjusting the speed at which the nozzle is oscillated, it isensured that an optimum degree of efficiency is achieved, becausecleaning can be effected with from very great to less adjacency andhence intensity with which the cleaning jet sweeps the inside of thetank.

By allowing the radius of the worm wheel to be less than that of thegear wheel, a rack movement is achieved which provides the nozzle withan angle of more than 180° in the vertical plane. The nozzle willtherefore be able to swing between an upper vertical position, in whichthe nozzle points upwards, and a lower inclined position in which thenozzle points at an angle downwards, pointing towards the furthermostarea of the bottom which experience has shown is the dirtiest, this areathus being effectively cleaned at the turning point of the nozzle.

By giving the worm wheel a variable degree of turning, the desiredpossibility of stepless adjustment of the speed of movement is achieved,and herewith of the speed at which the nozzle oscillates.

Finally, it is expedient to configure the adjustment as a limitation ofthe stroke length of the drive unit by means of a manually-rotatableeccentric disk, whereby a simple and reliable means of adjustment isachieved.

THE DRAWING

In the following section, an example embodiment of the invention will bedescribed in more detail with reference to the drawing, where

FIG. 1 shows an example of the mounting of the apparatus on the top of atank,

FIG. 2 shows the apparatus itself,

FIG. 3 shows the drive unit itself,

FIG. 4 shows a geometric illustration of a cycle in the degree of nozzleoscillation,

FIG. 5 shows a graph which depicts the angular position

of the nozzle in relation to time, and

FIG. 6 shows an example of a pattern of movement followed by a cleaningnozzle at the bottom of a tank.

DESCRIPTION OF THE EXAMPLE EMBODIMENT

In FIG. 1 is shown an example of the mounting of a cleaning apparatus 5on the top of separate tanks 1 or sections of the tank. The tank itselfcomprises the sides 2, the bottom 3 and the top on which the apparatus 5is mounted at a place 4 expedient for the cleaning.

Each apparatus 5 is provided with a nozzle 12 which can be traversedaround in the tank while at the same time it swings upwards anddownwards, as will be described later.

An embodiment of the actual cleaning apparatus 5 is shown in FIG. 2.

This comprises a drive unit for the nozzle, said drive unit beingoutside the tank and built into a housing 6 with a cover 7 and a flangeconnection 9 for Cleaning fluid 13, a turbine housing 8 and a mountingflange 10 for abutment against the top of the tank.

Extending inside the tank 1 there is a pipe 11 on the end of which thenozzle 12 is mounted in such a manner that it can be turned around inthe horizontal plane while at the same time it can be swung upwards anddownwards oscillating in an arc 41, as indicated in FIG. 2.

The mechanism for turning the nozzle 12 and for the regulation of thenozzle's pattern of movement inside the tank 1 will be described withreference to FIG. 3, where the housing 6, the cover 7, the flanges 9 and10 as well as the turbine housing 8 and the pipe 11 are indicated withstippled lines.

In the turbine housing 8 there is a turbine rotor 14 suspended in theflow of fluid 13 which is led from here down through the outer pipe 11to the nozzle at the end of the outer pipe 11.

The turbine rotor 14 drives a shaft 15 to which there is connected acrankwheel 16 with a crank 17. On this crank 17, suspended in a slidingmanner, there is a pushrod 18 which at its opposite end is connected toa rocker arm 19. The end of this rocker arm 19 is provided with aone-way clutch 20 of commonly-known type for the transfer of the rockingmovement to a turning movement on a worm shaft which is hereby turned inonly one direction.

The worm 21 on the shaft is in engagement with a worm wheel 22 which isturned as a result of the drive mechanism.

To the worm wheel 22 there is secured a downwardly-extending main shaft23. The nozzle 12 is mounted on the end of said shaft 23 in such amanner that the turning movement of the worm wheel 22 is transferred tothe nozzle 12, which is hereby rotated in the horizontal plane insidethe tank, as indicated in FIG. 2.

The speed of the turning movement depends solely on the speed ofrotation of the turbine rotor 14 and the gearing exchange effected bythe drive unit.

The turning speed can therefore only be regulated by means of anot-shown arrangement for the regulation of the flow of fluid 13 throughthe turbine housing 8, or by changing the stroke length of the crank 16,17.

In addition to this turning of the nozzle 12, the nozzle 12 is swivelledupwards and downwards in an oscillating movement 41, as indicated inFIG. 2.

This movement is brought about by a drive head 24 with an inclined slidesurface which lies up against a carrier arm 25. This arm 25 is providedwith a dog 27 which, assisted by a spring 28, lies up against aneccentric cam 29.

To the eccentric cam 29 there is fastened an adjustment wheel 30 so thatthe clearance of the carrier arm 25 in relation to the drive head 24 canbe adjusted in a stepless manner. The turning movement of a worm shaft31 which, via a one-way clutch 26 is mounted on the arm 25, 27, canhereby be steplessly varied.

The worm shaft 31 is in engagement with a worm wheel 32 which is mountedon a shaft 33. In the worm wheel 32 there is provided a stud 34 on whichthere is mounted a connecting link 35. At its opposite end, the link isconnected to a stud 36 on a pinion 38 which is mounted on an axle 37.

When the worm wheel 32 is turned, the pinion 38 is moved forwards andbackwards on the axle 37.

The pinion 38 is in toothed engagement with a rack 39 which extendstangentially to the pinion, and which is hereby moved upwards anddownwards while at the same time being rotated by the worm wheel 22. Atthe opposite end of the main shaft 23 there is mounted a rack 43 whichis in engagement with a pinion 42. The nozzle 12 is mounted on thispinion 42 in such a manner that the nozzle is swivelled upwards anddownwards in an arc 41, as indicated in FIGS. 2 and 4.

The speed, which is determined by the turning angle of the adjusting arm25 and herewith by the speed of rotation of the worm shaft 31, isdetermined by the position of the eccentric 29. Since this can bechanged in a stepless manner, the speed can hereby be varied from a lowto a higher speed, i.e. depending on the movement of the carrier arm 25by the drive head.

In order to clarify the forwards and backwards movement of the pinion38, the geometric relationships are depicted in FIG. 4, where the pinion38 is indicated turning around its axis 37. The connecting link 35extends between the points of application 36 and 34 on the worm wheel 32which turns around its axis 33.

It will be noted that the radius of the worm wheel 32 is less than theradius of the pinion 38.

With stippled lines, FIG. 4 also shows the rack 39 which at its oppositeend of the main shaft 23 is provided with a rack 43 which is inengagement with the nozzle's 12 pinion 42.

It appears clearly from the drawing that when the pinion 38 is movedover an angle of more than 180°, then the nozzle's pinion 42 will bemade to effect a turning movement of more than 180°.

For the sake of clarity, there is sketched in a given position of thevectors between the centres 33 and 37 and the studs 34 and 36.

By changing the radius of the worm wheel 32 to the stud 34 and thelength of the connecting link 35, both the length of the swivellingmovement 41 of the nozzle 12 as well as the turning angle of the nozzle12 can be adjusted. These can hereby be adjusted for the individualtank.

The following is a description of the mode of operation of the cleaningapparatus:

In FIG. 6, it is indicated with curves 40 how the intensity of the jetextends inside a tank. The cleaning apparatus is envisaged as beingplaced in the centre 4 at the top of the tank, and in this case thenozzle 12 is dimensioned to be swivelled in an arc of 180° from thevertical up to the vertical down.

The start position of the nozzle is upwardly-directed, and it is seenthat it distributes the jet uniformly in the tank during its movement.The closeness of the curved lines 40 indicates that the nozzle isoperated at a low swivelling speed. This is adjusted via the rotary disk30 for short angular rotation over the eccentric 29, which provides onlya short rocking movement of the arm 25 and herewith slow rotation of theworm shaft 31 and therewith finally limited movement of the rack 39 andherewith the pinion 42, as indicated in FIGS. 3 and 4.

When a more dispersed cleaning pattern is desired with greater nozzleswivelling speed, the eccentric 29 must be turned towards greaterangular rotation and herewith greater rocking movement of the arm 25 toproduce a high speed of rotation of the pinion 42 at the nozzle.

The cleaning intensity can be steplessly adjusted to ensure adequatecleaning of the tank and no more. This is naturally of great importancefor the economy, in that there is no need to clean more than necessary,and that this adjustment of the intensity can take place by steplessadjustment.

Since there is normally a need for extra cleaning particularly of thecorners at the bottom, it is expedient to use a construction like thatwhich is shown in FIG. 4, where the nozzle can turn at the furthermostcorners, in that the rocking movement can extend from the vertical andpointing to opposite corners.

FIG. 5 shows graphically how the nozzle 12 and herewith the jet areoriented for most of the time, the absciss, in the area between 50° and-50°, which is just above the bottom, while the 180° on the ordinatemeans that the nozzle points upwards for a shorter period of time.

From this it will be clear that an extraordinarily effective cleaning isachieved of precisely those areas inside the tank which are normally themost dirty. An attempt to illustrate this is also made in FIG. 6, whichshows the cleaning which is achieved in the corners where the nozzleturns, and where the cleaning intensity of the jet path 40 is at itsgreatest.

This cleaning pattern is unique for the apparatus and provides ahitherto-unknown high degree of efficiency, and herewith savings in bothenergy and cleaning fluid as well as time.

The apparatus can be provided in a commonly-known manner with indicatorsfor the nozzle's position both in the vertical and the horizontalplanes, so that the starting position for the nozzle can be adjusted inaccordance with requirements before the cleaning commences.

The speed at which the nozzle is swivelled can be read from the rotarydisk on the eccentric, and herewith the intensity of the cleaningpattern.

Where there is need for a programmed control of the cleaning pattern,the eccentric can be made rotatable by means of a servo motor, wherebyan adjustment and regulation can be effected for achieving the mostexpedient cleaning for the individual tanks.

I claim:
 1. An apparatus for cleaning the inside surfaces of a tankcomprising a nozzle lowered into the tank, a jet of fluid issuing fromthe nozzle for cleaning the inside surfaces of the tank, the nozzlebeing capable of being rotated around a first axis and being capable ofbeing swivelled upward and downward in an oscillating movement around asecond axis at right angles to the first axis in a predetermined manner,so that the jet of fluid is traversed around the first axis at the sametime that the jet is moved upwards and downwards inside the tank, aturbine, driven by a stream of fluid, drive means connected to theturbine for rotating the nozzle, the drive means having a worm shaft, aworm wheel engaged with the worm shaft, a first stud provided on theworm wheel, a first pinion having a second stud thereon, a connectinglink having a first link end in sliding engagement with the first studon the worm wheel, a second link end in sliding engagement with thesecond stud on the first pinion such that rotation of the worm wheelmoves the first pinion forwards and backwards, a rack having a first endand a second end, the first pinion being in engagement with the firstend of the rack, a second pinion connected to the nozzle, the second endof the rack in engagement with the second pinion for effecting theswiveling upward and downward oscillating movement of the nozzle.
 2. Theapparatus according to claim 1, wherein a radius of the first stud isless than a radius of the second stud.
 3. The apparatus according toclaim 2, further comprising turning the worm shaft using a variabledrive unit.
 4. The apparatus according to claim 3, further comprisingproviding a rotatable eccentric disk for limiting a stroke length of thedrive unit and thereby limiting the turning of the worm shaft.
 5. Theapparatus according to claim 1, further comprising turning the wormshaft using a variable drive unit.
 6. The apparatus according to claim5, further comprising providing a rotatable eccentric disk for limitinga stroke length of the drive unit and thereby limiting the turning ofthe worm shaft.